Can I edit the image of the grey sad face?

I am using the AdguardDNS service at the moment and in place of where the advertisements should be, I see a bunch of rectangles and squares featuring a grey sad face. I would like to change this icon to display a happy face because not seeing advertisements is something to smile about. I use Pop!_OS 18.10 (Ubuntu based) on my laptop and Android 4.4.2 on my smartphone.